F-21 jet fighter engine diffusion bonding development

Brief reference. Pratt & Whitney development of titanium diffusion bonding for the engine. Tom shows part as visual aid (mentioned: "I think I've shown it to you before"). Tom mis-stated as "F20"; bracketed [F-21] per convention.

Stage two: you will actually have some of those interfacial grain boundaries remaining, but some of the voids will get trapped on the inside of the grains. The third stage is when you trap the voids and you no longer have any of that original interface grain boundary. The grains have recrystallized and grown across the interface, and except for those porosities, you now have a perfect joint. Diffusion bonding is one of the ways to get a near-perfect joint. This is part of a development of titanium diffusion bonding for the F-20 [F-21] — is that the Raptor? — for one of the engines they did down at Pratt and Whitney.

Diffusion-bonded titanium part from Pratt & Whitney research labs, recovered by a former student who had worked on engine joining technology for the F-22 program (Tom said "F-21"; corrected to F-22).

[Tom holds up a diffusion-bonded titanium part.] We use diffusion bonding. This is a piece of titanium that was part of the development project for the F-21 [F-22] jet fighter. One of the students who was in the class gave this to me — he had recovered it when he was working at Pratt & Whitney research labs, and they were developing the engine and the joining technology of how to put together the jet engine. That's a type of diffusion bonding.